1. Field of the Invention
The object of the present invention is a calendar watch movement comprising at least one intermittently advancing calendar-indicating member provided with a toothing, and a drive mechanism comprising a driving member driven in rotation continuously by the movement, at least one drive member cooperating with the toothing of the said indicating member to cause its intermittent advance, and a coupling with angular play between the drive member and a driven member also forming part of said mechanism.
2. Description of the Prior Art
The German Patent Application (German unexamined application for Pat. No. 25 46 643) describes a watch movement without coupling with angular play, in which a calendar wheel of simple construction cooperates directly via drive members, with the toothing of a date ring and with the toothing of a day star. The calendar wheel extends partially below the date ring but, in view of its small size, it can be housed in a recess in the pillar plate, so that it does not increase the thickness of the movement. However, this known calendar movement does not assure an instantaneous advance of the calendar indicating members, which is considered in practice to be a major drawback.
Other calendar watch movements, known in particular from Swiss Pat. Nos. 473,417 and 575,140, comprise calendar mechanisms which assure an instantaneous advance of the indicating member or members. The mechanism in accordance with Swiss Pat. No. 473,417 uses a coupling with angular play between a calendar wheel which is driven continuously at the rate of one revolution per 24 hours and a cam which is acted on by a rapid-advance member and which bears a finger for the driving of the date ring. However, this construction does not assure the driving of a date ring located at the periphery of the movement, and the arrangement of the calendar wheel and of the rapid-advance member leads to a bulkier embodiment than the arrangement of the movement described in the aforementioned German patent application.